According to TMZ, the 84-year-old died from a suspected stroke on Wednesday, December 28.
Her son Todd Fisher, 58, confirmed the awful news, telling the site: "She's with Carrie."
Todd also revealed her heartbreaking last words were: "I miss her so much, I want to be with Carrie."
Just yesterday, Debbie paid tribute to her beloved daughter with a touching Facebook post.
“Thank you to everyone who has embraced the gifts and talents of my beloved and amazing daughter,” she penned.
“I am grateful for your thoughts and prayers that are now guiding her to her next stop.”
Earlier that afternoon Todd was also thinking of his late sister, taking to Twitter to post a flashback of his family.
According to TMZ, veteran actress Debbie was rushed to the hospital after suffering a stroke.
In a horrible turn of events, the beloved star is believed to have been at her son Todd's Beverley Hills home making arrangements for her daughter's funeral when she fell ill.
The news comes less than a day after Debbie's daughter, Carrie Fisher, passed away from a heart attack.
The 60-year-old Star Wars actress was on a 11 hour flight from London to LA on Friday when she went into cardiac arrest.
Debbie rose to fame thanks to her role in the 1952 classic Singin' in the Rain.
She went on to star in a number of Hollywood films including Tammy and the Bachelor and The Unsinkable Molly Brown, for which she received an Oscar nomination for.
In 1959, she divorced husband Eddie Fisher after he had an affair with Elizabeth Taylor. She went on to remarry Harry Karl and Richard Hamlett but neither marriage lasted.
Speaking of her tight-knit family, she once mused: "I live right in front of my daughter. I have a little house right in front of her because I can stay in touch."
"It's like a little commune, and it's very nice, because you can be close. I can see my granddaughter. I live very close to my brother, too, and my son. We're a very close family."
As for her incredible career, the Texan born beauty never expected to enjoy such success.
"I never dreamt of being in the movies. I was from a very average, I would say, a rather poor family, so my big treat was to work hard all week - I mowed lawns and babysat and washed dishes and washed cars - to go to the movies."
She is survived by her son Todd and granddaughter, actress Billie Lourd, 24.